Molecular regulatory mechanisms which function in regulation of gene expression in fertilization, development, and control of growth will be examined. These studies involve the utilization of maternal mRNA and the production of messenger RNA during development and its relationship to transcription and heterogeneous nuclear RNA production. Specific goals for this year include: 1) To use cDNA probes against maternal mRNA to elucidate the activation, use, and decay of maternal mRNA in terms of the specific sequences with the without poly (A) and those on and off the polysomes. 2) To define the mRNA sequences which are accumulated at blastula stage but not pluteus stage to determine if they are transcribed into hnRNA at pluteus stage but not stabilized and transported to the cytoplasm. Alternatively, the accumulation of these mRNA molecules would be regulated transcriptionally. 3) To define the prevalent class of nuclear RNA transcripts and to determine if these are regulated during development even if most of the sequences, the complex class, are not regulated. The idea is that some genes have to be very much more active at certain stages and that these would be present in larger numbers in the nuclear RNA of that stage. Thus the prevalent class should change.